1. Field of the Invention
The present invention relates to a multiple disc clutch apparatus which transfers or interrupts a driving force from an input member and more particularly to a multiple disc clutch apparatus which includes a cam mechanism for suppressing an action of a reverse driving force from an output shaft towards the input member side.
2. Background Art
There is known, as a conventional multiple disc clutch apparatus, a multiple disc clutch apparatus provided with an clutch outer member which is coupled to an input member, a clutch inner member which is fixed to an output member, a plurality of primary friction discs which are brought into engagement with the clutch outer member so as not to rotate relatively, a plurality of secondary friction discs which are disposed alternately with the primary friction discs in an axial direction, a clutch center member with which the secondary friction discs are brought into engagement so as not to rotate relatively, a pressure plate which holds the primary friction discs and the secondary friction discs in the axial direction between the clutch inner member and itself, a clutch spring which biases the pressure plate towards a side where the primary friction discs and the secondary friction discs are brought into press contact, and a cam mechanism which is provided between the clutch inner member and the clutch center member for transferring a driving force from the input member from the clutch center member to the clutch inner member and pressing the pressure plate via the clutch center member against the biasing force of the clutch spring towards a side where the pressure plate is spaced away from the clutch inner member when a reverse driving force acts thereon from the output member, wherein the cam mechanism has a projecting cam and a recess cam, as well as a primary inclined surface and a secondary inclined surface which are inclined in the same direction relative to a circumferential direction, and wherein the projecting cam and the recess cam are brought into point contact with each other (for example, refer to JP-A-2008-106846).
In the conventional multiple disc clutch apparatus, in order to cause the clutch center member to slide in the axial direction smoothly, some clearance is provided in the sliding portion. However, this clearance so provided offsets a rotating axis of the clutch center member with respect to a rotating axis of the clutch inner member, and this causes the clutch center member to fall (incline), leading to the possibility that the feeling is affected which is felt by the driver when he or she engages or disengages the clutch. In the multiple disc clutch apparatus described in JP-A-2008-106846, since the projecting cam and the recess cam contact each other at a point, the fall of the clutch center member tends to occur easily, a countermeasure against which has been desired.